Structured light 3d sensors with variable focal length lenses and illuminators

ABSTRACT

A method for three-dimensional imaging includes emitting an output light with a structured light illuminator in a structured light pattern, receiving a trigger command, changing a field of illumination of the illuminator, and changing a field of view of an imaging sensor. The field of view and the field of illumination are linked, such that the field of view of the imaging sensor is the same as the field of illumination of the illuminator at a short throw field of view and a long throw field of view. The method further includes detecting a reflected light with the imaging sensor and measuring a depth value by calculating a distortion of the structured light pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.15/371,087, filed Dec. 6, 2016, which is hereby incorporated byreference in its entirety.

BACKGROUND Background and Relevant Art

Three-dimensional (3D) imaging systems use configured to identify andmap a target based on light that is reflected from the target. Many ofthese imaging systems are configured with a light source that isconfigured to emit light towards the target a photoreceptor to receivethe light after it is reflected back from the target.

Some imaging systems (i.e., time-of-flight imaging systems) are capableof identifying the distances and positions of objects within a targetenvironment at any given time by measuring the elapsed time between theemission of light from the light source and the reception of the lightthat is reflected off of the objects.

Other imaging systems (e.g., structured light systems) measure thedistortion or displacement of light patterns to measure the shapes,surfaces and distances of the target objects. For instance, light may beemitted as a structured pattern, such as a grid pattern, dot pattern,line pattern, etc., towards the target environment. Then, thephotoreceptor receives light that is reflected back from the targetobjects which is also patterned and which is correlated against theknown initial pattern to calculate the distances, shapes, and positionsof the objects in the target environment.

However, contamination of ambient light in the reflected light/imagescan degrade the 3D imaging quality. For example, objects that are faraway can reflect light at a much lower intensity than close objects.Additionally, brightly illuminated environments, such as outdoorenvironments during daylight, can also introduce noise through ambientlight.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced.

BRIEF SUMMARY

In some embodiments, a method for three-dimensional imaging includesemitting an output light with a structured light illuminator in astructured light pattern, receiving a trigger command, changing a fieldof illumination of the illuminator, and changing a field of view of animaging sensor. The field of view and the field of illumination arelinked, such that the field of view of the imaging sensor is the same asthe field of illumination of the illuminator at a short throw field ofview and a long throw field of view. The method further includesdetecting a reflected light with the imaging sensor and measuring adepth value by calculating a distortion of the structured light pattern.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

Additional features and advantages will be set forth in the descriptionwhich follows, and in part will be obvious from the description, or maybe learned by the practice of the teachings herein. Features andadvantages of the invention may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. Features of the present invention will become more fullyapparent from the following description and appended claims, or may belearned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features can be obtained, a more particular descriptionof the subject matter briefly described above will be rendered byreference to specific embodiments which are illustrated in the appendeddrawings. For better understanding, the like elements have beendesignated by like reference numbers throughout the various accompanyingfigures. While some of the drawings may be schematic or exaggeratedrepresentations of concepts, at least some of the drawings may be drawnto scale. Understanding that these drawings depict only typicalembodiments and are not therefore to be considered to be limiting inscope, embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a schematic representation of a three-dimensional (3D)time-of-flight (TOF) imaging system having adjustable illuminator andimaging optics;

FIG. 2 is a schematic representation of the 3D TOF imaging system ofFIG. 1 in a short throw imaging mode;

FIG. 3 is a schematic representation of the 3D TOF imaging system ofFIG. 1 in a long throw imaging mode;

FIG. 4 is a comparison of a cropped region of an imaging sensor in aconventional long throw imaging mode to an active area of the 3D TOFimaging system of FIG. 1 in a long throw imaging mode;

FIG. 5-1 is a schematic representation of a TOF illuminator withadjustable illumination optics;

FIG. 5-2 is a schematic representation of an imaging sensor withadjustable imaging optics;

FIG. 6 is a schematic representation of a 3D structured light imagingsystem in a short throw imaging mode;

FIG. 7 is a schematic representation of the 3D structured light imagingsystem of FIG. 6 in a long throw imaging mode;

FIG. 8 is a schematic representation of a structured light illuminatorwith adjustable optics;

FIG. 9 is a schematic representation of a 3D active stereoscopic imagingsystem in a short throw imaging mode;

FIG. 10 is a schematic representation of the 3D active stereoscopicimaging system of FIG. 9 in a long throw imaging mode;

FIG. 11 is a schematic representation of a 3D passive stereoscopicimaging system in a short throw imaging mode;

FIG. 12 is a schematic representation of the 3D passive stereoscopicimaging system of FIG. 11 in a long throw imaging mode;

FIG. 13 is a schematic representation of a 3D imaging system with anilluminator with adjustable optics encountering a multipath error;

FIG. 14 is a schematic representation of the 3D imaging system of FIG.13 in a long throw operating mode to avoid the multipath error;

FIG. 15 is a schematic representation of the 3D imaging system of FIG.13 with a partially blocked illuminator to avoid the multipath error;

FIG. 16 is a flowchart illustrating a method of 3D imaging with a 3Dimaging system according to the present disclosure including an activeilluminator; and

FIG. 17 is a flowchart illustrating a method of 3D imaging with a 3Dimaging system according to the present disclosure with passiveillumination.

DETAILED DESCRIPTION

Disclosed embodiments include improved imaging systems, as well asdevices, systems, and methods for improving efficiency and resolution inthree-dimensional (3D) imaging.

With regard to the following disclosure, it will be appreciated that inthe development of the disclosed embodiment(s), as in any engineering ordesign project, numerous embodiment-specific decisions will be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneembodiment to another. It will further be appreciated that such adevelopment effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

In some embodiments, the accuracy by which a target and/or anenvironment may be imaged with a 3D imaging system may be at leastpartially related to ratio of reflected light (light emitted from theimaging system and reflected back to the imaging system) and ambientlight captured by imaging system. The reflected light captured may beincreased by increasing the intensity or by altering the field ofillumination of the emitted light. In other embodiments, the accuracy bywhich a target and/or an environment may be imaged with a 3D imagingsystem may be at least partially related to the angular resolution withwhich the reflected light is collected and the accuracy with which theposition of visual features may be recognized.

In some embodiments, a 3D imaging system may include one or more lensesto allow adjustment of a field of illumination of one or moreilluminators and/or a field of view of one or more imaging sensors. Forexample, a 3D imaging system may include an illuminator with anadjustable focal length and an imaging sensor with an adjustable focallength. Altering the focal length of the illuminator and/or the imagingsensor may change the angular resolution of the 3D imaging system. Insome embodiments, the 3D imaging system may broaden a field ofillumination and/or view to allow tracking of objects within a largerarea close to the 3D imaging system. In other embodiments, the 3Dimaging system may narrow a field of illumination and/or view toincrease angular resolution at longer distances to more preciselyidentify and/or track features at longer distances.

FIG. 1 illustrates a 3D imaging system 100 including a housing 102 thatsupports an illuminator 104 and an imaging sensor 106. The illuminator104 and imaging sensor 106 are in data communication with a processor101. In some embodiments, the illuminator 104 is a modulated illuminatorand the processor 101 may be a time-of-flight measurement device. Forexample, the illuminator 104 may emit an output light 107 that ismodulated over time. In some embodiments, the output light 107 ismodulated by frequency over time. In other embodiments, the output light107 is modulated by intensity over time. In yet other embodiments, theoutput light 107 is modulated by other values of the output light 107,such as a pulse duration. The imaging sensor 106 has a coordinatedshutter that operates in conjunction with the light modulation, allowingthe time of flight depth measurement.

In some embodiments, the illuminator 104 provides an output light 107 ina first wavelength range. For example, the first wavelength range may bein the infrared wavelength range. In other examples, the firstwavelength range may be in the ultraviolet range. In yet other examples,the first wavelength range may be in the visible wavelength range. Insome embodiments, the first wavelength range has a maximum intensity ina range having an upper value, a lower value, or upper and lower valuesincluding any of 800 nanometers (nm), 810 nm, 820 nm, 830 nm, 840 nm,850 nm, 860 nm, 870 nm, 880 nm, 890 nm, 900 nm, 910 nm, 920 nm, 930 nm,940 nm, 950 nm, 960 nm, 970 nm, 980 nm, 990 nm, 1000 nm, or any valuestherebetween. For example, the first wavelength range may have a maximumintensity greater than 800 nm. In other examples, the first wavelengthrange may have a maximum intensity less than 1000 nm. In yet otherexamples, the first wavelength range may have a maximum intensitybetween 800 nm and 1000 nm. In further examples, the first wavelengthrange may have a maximum intensity between 825 nm and 875 nm. In atleast one example, the first wavelength range may have a maximumintensity about 850 nm.

The imaging sensor 106 is oriented to receive input light 109 thatincludes at least a portion of the output light 107 reflected from atarget or object in the environment around the 3D imaging system 100.For example, the illuminator 104 and imaging sensor 106 are orientedwith substantially parallel axes. In other embodiments, the illuminator104 and imaging sensor 106 may be oriented with convergent axes ordivergent axes. For example, the illuminator 104 and imaging sensor 106may be oriented with axes that converge at a predetermined distance fromthe 3D imaging system 100. Convergence axes of the illuminator 104 andimaging sensor 106 may allow for increased performance at intended orexpected operating distances. For example, a 3D imaging systemintegrated with a head mounted display may be configured to haveconvergent axes that converge at or near a user's arm length for handgesture recognition.

In some embodiments, the imaging sensor 106 includes one or morephotoreceptors. For example, the imaging sensor 106 may include an arrayof photoreceptors to capture an image of an illuminated target or objectin the environment. The photoreceptors may be configured to receive anddetect input light 109 including at least a portion of the output light107 reflected toward the imaging sensor 106. In some embodiments, theimaging sensor 106 is configured to receive and detect input light 109in the first wavelength range.

The housing 102 may be a standalone housing or integrated into anotherdevice or system. In some embodiments, the housing 102 is a wearabledevice, such as a head mounted display. In other embodiments, thehousing 102 is part of another device, such as a vehicle. For example,the 3D imaging system 100 may be integrated into a motorized ornon-motorized vehicle (such as an automobile, an aerial vehicle, abicycle, a motorcycle, a wheelchair, etc.) to provide 3D imaging system100 in a mobile environment. In some examples, the 3D imaging system 100may be integrated into an automobile, such as in the front bumper, todetect pedestrians, animals, or other road hazards the automobile mayencounter. A 3D imaging system 100 according to the present disclosuremay allow for long-range 3D sensing for high-speed highway applications,while allowing for improved wide-angle 3D sensing for low-speedresidential or parking lot applications with the same 3D imaging system100. In other examples, the 3D imaging system 100 may be integrated intoaerial vehicles, such as drones, for long-range high altitude 3Dsensing, while allowing for improved wide-angle 3D sensing fornavigating confined spaces.

The illuminator 104 may include one or more illuminator lenses foraltering the field of illumination (FOI) of the illuminator 104. In someembodiments, one or more illuminator lens is positioned proximate anoutput of the illuminator 104 and movable relative to a light source tochange a focal length of the illuminator 104. For example, theilluminator 104 may have a short throw FOI 108 and a long throw FOI 112.The short throw FOI 108 may provide a wider FOI with lower illuminationconcentration for a given light source intensity. The lower illuminationconcentration may limit the effective range of the illuminator whileoperating in the short throw FOI 108.

The long throw FOI 112 provides greater illumination concentration for agiven light source intensity compared to the short throw FOI 108. Thelong throw FOI 112, therefore, may allow for the 3D imaging system toselectively increase illumination on distance objects. Increasedillumination concentration may allow the 3D imaging system 100 toincrease the illumination range and/or allow the 3D imaging system 100to illuminate objects in higher amounts of ambient light. For example,the illuminator 104 may operate in a long throw FOI 112 when the 3Dimaging system 100 is used outdoors in sunlight.

To operate outdoors in sunlight, the 3D imaging system 100 must generatelight that is detectable over the ambient light. The illuminator 304,therefore, may generate output light with intensity sufficient toprovide detectability in sunlight by the imaging sensor. For example,the illuminator 304 may generate output light at a pulsed rate of 10Watts per meter squared or greater. In other examples, the illuminator304 may generate output light at a pulsed rate of 50 Watts per metersquared or greater. In a structured light illuminator example, theilluminator may provide peak intensity values within the FOI (e.g., atnodes of the structured light) of 10 Watts per meter squared or greaterin pulsed operation. In other structured light illuminator examples, theilluminator may provide peak intensity values within the FOI of 50 Wattsper meter squared or greater in pulsed operation.

When the imaging sensor includes a bandpass filter, such as an IRfilter, the illumination intensity is relative to the ambient intensityin the range that is transmitted through the bandpass filter. Forexample, full direct sunlight is about 100-150 klux, where 1 klux is1.168 μW/(cm²*nm). In some embodiments, the illuminator 304 providessufficient illumination to be detectable over the sunlight in the rangeof light transmitted to the imaging sensor.

The illumination concentration increases relative to the angle of theFOI. The surface at the projected end of the FOI may be considered ashaving a spherical cap. The surface area of a spherical cap is:

A=2πr ²(1−cos θ)

Where theta is the angle subtending a spherical cap of radius r. Depthperformance is at least partially defined by the radial depth. Theradial power density may be increased by reducing the field ofillumination and field of view to concentrate the output light, or byincreasing the illumination intensity, by increasing the activelyilluminated exposure time, or combinations thereof.

The imaging sensor 106 may include one or more imaging lenses to alter afield of view (FOV) of the imaging sensor 106. In some embodiments, oneor more imaging lenses is positioned proximate an input of the imagingsensor 106 and movable relative to one or more photoreceptors to changean effective focal length of the imaging lens. For example, the imagingsensor 106 may have a short throw FOV 110 and a long throw FOV 114. Theshort throw FOV 110 may provide a wider FOV to track nearby objects inthe environment around the 3D imaging system 100.

The long throw FOV 114 provides smaller angular resolution to identifyand track objects at longer distances than the short throw FOV 114. Thelong throw FOV 114 therefore, may allow for the 3D imaging system toincrease imaging resolution depending on task. The imaging sensor 106has a photoreceptor array with a fixed pixel resolution. By decreasingthe FOV of the imaging sensor 106 in the long throw FOV 114, each pixelof the photoreceptor array may receive a smaller angular arc of theinput light 109, increasing the resolution of the imaging sensor 106 onthe center of the FOV.

FIG. 2 illustrates the 3D imaging system 100 of FIG. 1 in a short-rangeapplication. The 3D imaging system 100 may operate in a short rangeapplication when identifying and/or tracking objects 122 that arerelatively close to the illuminator 104 and/or imaging sensor 106. Insome embodiments, the illuminator 104 and/or imaging sensor 106 areconfigured to identify or track a close object 122 that is a firstdistance 116 from the illuminator 104 and/or imaging sensor 106. In someembodiments, the first distance 116 is in a range having an upper value,a lower value, or an upper and lower value including any of 15centimeters (cm), 30 cm, 60 cm, 1.0 meters (m), 1.5 m, 2.0 m, 3.0 m, 5.0m, or any values therebetween. For example, the first distance 116 maybe greater than 15 cm. In other examples, the first distance 116 may beless than 5.0 m. In yet other examples, the first distance 116 may bebetween 15 cm and 5.0 m. In further examples, the first distance 116 maybe between 30 cm and 3.0 m. In at least one example, the first distance116 may be between 60 cm and 2.0 m.

In some embodiments, the short throw FOI 108 is substantially conical,matching the FOV of the camera system. In other embodiments, the shortthrow FOI 108 is hexagonal, square, or rectangular. For example, theilluminator 104 may emit light that is projected in an approximaterectangle. At the first distance 116, the short throw FOI 108 may have ashort throw FOI width 118 that is at least partially related to a shortthrow FOI angle 119. In some embodiments, the short throw FOI width 118is in a range having an upper value, a lower value, or an upper andlower value including any of 30 cm, 60 cm, 1.0 m, 1.5 m, 2.0 m, 3.0 m,5.0 m, 10 m, or any values therebetween. For example, the short throwFOI width 118 may be greater than 30 cm. In other examples, the shortthrow FOI width 118 may be less than 10 m. In yet other examples, theshort throw FOI width 118 may be between 30 cm and 10 m. In furtherexamples, the short throw FOI width 118 may be between 60 cm and 5.0 m.In at least one example, the short throw FOI width 118 may be between1.0 m and 3.0 m.

In some embodiments, the short throw FOI angle 119 is in a range havingan upper value, a lower value, or upper and lower values including anyof 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, or any valuestherebetween. For example, the short throw FOI angle 119 may be greaterthan 60°. In other examples, the short throw FOI angle 119 may be lessthan 150°. In yet other examples, the short throw FOI angle 119 may bebetween 60° and 150°.

The imaging sensor 106 may have a short throw FOV 110. In someembodiments, the short throw FOV 110 is substantially equivalent to theshort throw FOI 108. In other embodiments, the short throw FOV 110 isindependent of the short throw FOI 108.

In some embodiments, the short throw FOV 110 is substantially conical.In other embodiments, the short throw FOV 110 is hexagonal, square, orrectangular. At the first distance 116, the short throw FOV 110 may havea short throw FOV width 120 that is at least partially related to ashort throw FOV angle 121. In some embodiments, the short throw FOVwidth 120 is in a range having an upper value, a lower value, or anupper and lower value including any of 30 cm, 60 cm, 1.0 m, 1.5 m, 2.0m, 3.0 m, 5.0 m, 10 m, or any values therebetween. For example, theshort throw FOV width 120 may be greater than 30 cm. In other examples,the short throw FOV width 120 may be less than 10 m. In yet otherexamples, the short throw FOV width 120 may be between 30 cm and 10 m.In further examples, the short throw FOV width 120 may be between 60 cmand 5.0 m. In at least one example, the short throw FOV width 120 may bebetween 1.0 m and 3.0 m.

In some embodiments, the short throw FOV angle 121 is in a range havingan upper value, a lower value, or upper and lower values including anyof 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, or any valuestherebetween. For example, the short throw FOV angle 121 may be greaterthan 60°. In other examples, the short throw FOV angle 121 may be lessthan 150°. In yet other examples, the short throw FOV angle 121 may bebetween 60° and 150°.

At the first distance 116, the short throw FOI 108 and the short throwFOV 110 overlap. In some embodiments, at the first distance 116, theshort throw FOI 108 and the short throw FOV 110 overlap by at least 50%,at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, orany values therebetween.

The FOI and the FOV of the 3D imaging system 100 may be continuouslyvariable between the short throw FOI 108 and/or FOV 110 and a long throwFOI 112 and long throw FOV 114, shown in FIG. 3. One or more illuminatorlenses in the illuminator 104 may move to alter the FOI to the longthrow FOI 112. In some embodiments, the one or more illuminator lensesin the illuminator 104 are moved by a piezoelectric motor, by steppermotor, or by other mechanical or electromechanical motor.

The 3D imaging system 100 may operate in a long range application whenidentifying and/or tracking objects 124 that are relatively far from theilluminator 104 and/or imaging sensor 106. In some embodiments, theilluminator 104 and/or imaging sensor 106 are configured to identify ortrack a distant object 124 that is a second distance 126 from theilluminator 104 and/or imaging sensor 106. In some embodiments, thesecond distance 126 is in a range having an upper value, a lower value,or an upper and lower value including any of 1.0 m, 2.0 m, 3.0 m, 5.0 m,7.0 m, 9.0 m, 12.0 m, 15.0 m, or any values therebetween. For example,the second distance 126 may be greater than 1.0 m. In other examples,the second distance 126 may be less than 15.0 m. In yet other examples,the second distance 126 may be between 1.0 m and 15.0 m. In furtherexamples, the second distance 126 may be between 2.0 and 12.0 m. In atleast one example, the second distance 126 may be about 3.0 m.

In some embodiments, the long throw FOI 112 is substantially conical. Inother embodiments, the long throw FOI 112 is hexagonal, square, orrectangular. For example, the illuminator 104 may emit light that isprojected in an approximate rectangle. At the second distance 126, thelong throw FOI 112 may have a long throw FOI width 128 that is at leastpartially related to a long throw FOI angle 129. In some embodiments,the long throw FOI width 128 is in a range having an upper value, alower value, or an upper and lower value including any of 30 cm, 60 cm,1.0 m, 1.5 m, 2.0 m, 3.0 m, 5.0 m, 10 m, or any values therebetween. Forexample, the long throw FOI width 128 may be greater than 30 cm. Inother examples, the long throw FOI width 128 may be less than 10 m. Inyet other examples, the long throw FOI width 128 may be between 30 cmand 10 m. In further examples, the long throw FOI width 128 may bebetween 60 cm and 5.0 m. In at least one example, the long throw FOIwidth 128 may be between 1.0 m and 3.0 m.

In some embodiments, the long throw FOI angle 129 is in a range havingan upper value, a lower value, or upper and lower values including anyof 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or any valuestherebetween. For example, the long throw FOI angle 129 may be greaterthan 5°. In other examples, the long throw FOI angle 129 may be lessthan 90°. In yet other examples, the long throw FOI angle 129 may bebetween 5° and 90°.

In some embodiments, the illuminator 104 has a range of FOI (e.g., fromthe short throw FOI angle 119 to the long throw FOI angle 129) in arange having an upper value, a lower value, or upper and lower valuesincluding any of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°,110°, 120°, or any values therebetween. For example, the FOI range maybe greater than a 10° range. In other examples, the FOI range may beless than a 120° range. In yet other examples, the FOI range may bebetween a 10° range and a 120° range. In at least one example, the FOIrange is a 120° range.

The imaging sensor 106 may have a long throw FOV 114. In someembodiments, the long throw FOV 114 is substantially equivalent to thelong throw FOI 112. In other embodiments, the long throw FOV 114 isindependent of the long throw FOI 112.

In some embodiments, the long throw FOV 114 is substantially conical. Inother embodiments, the long throw FOV 114 is pyramidal. At the seconddistance 126, the long throw FOV 114 may have a long throw FOV width 130that is at least partially related to a long throw FOV angle 131. Insome embodiments, the long throw FOV width 130 is in a range having anupper value, a lower value, or an upper and lower value including any of30 cm, 60 cm, 1.0 m, 1.5 m, 2.0 m, 3.0 m, 5.0 m, 10 m, or any valuestherebetween. For example, the long throw FOV width 130 may be greaterthan 30 cm. In other examples, the long throw FOV width 130 may be lessthan 10 m. In yet other examples, the long throw FOV width 130 may bebetween 30 cm and 10 m. In further examples, the long throw FOV width130 may be between 60 cm and 5.0 m. In at least one example, the longthrow FOV width 130 may be between 1.0 m and 3.0 m.

In some embodiments, the long throw FOV angle 131 is in a range havingan upper value, a lower value, or upper and lower values including anyof 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or any valuestherebetween. For example, the long throw FOV angle 131 may be greaterthan 5°. In other examples, the long throw FOV angle 131 may be lessthan 90°. In yet other examples, the long throw FOV angle 131 may bebetween 5° and 90°.

In some embodiments, the imaging sensor 106 has a range of FOV (e.g.,from the short throw FOV angle 121 to the long throw FOV angle 131) in arange having an upper value, a lower value, or upper and lower valuesincluding any of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°,110°, 120°, or any values therebetween. For example, the FOV range maybe greater than a 10° range. In other examples, the FOV range may beless than a 120° range. In yet other examples, the FOV range may bebetween a 10° range and a 120° range. In at least one example, the FOVrange is a 120° range.

At the second distance 126, the long throw FOI 112 and the long throwFOV 114 overlap. In some embodiments, at the second distance 126, thelong throw FOI 112 and the long throw FOV 114 overlap by at least 50%,at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, orany values therebetween.

FIG. 4 illustrates an embodiment of a photoreceptor array 132 that maybe used in the imaging sensor. In some embodiments, the photoreceptorarray 132 is a complimentary metal-oxide semiconductor (CMOS) sensor. Inother embodiments, the photoreceptor array 132 is a charge coupleddevice (CCD).

The photoreceptor array 132 has a height 134 and a width 136 of theactive area. In conventional long throw systems, a cropped subsection ofthe photoreceptor array 132 having a reduced height 138 and reducedwidth 140 is used to image the smaller angular space that is illuminatedby the illuminator. For example, in some conventional systems, the FOVis cropped from 512×512 down to 320×288, a >60% reduction in overallresolution. Using a portion of the photoreceptor array 132 that is lessthan the full height 134 and width 136 of the active area limits theangular resolution of the 3D imaging system and the associated optics.In some embodiments according to the present disclosure, adjustableoptics may allow for the imaging sensor to image input light withsubstantially all of the height 134 and width 136 of the photoreceptorarray 132. For example, the adjustable optics of the illuminator andimaging sensor may allow for the imaging sensor to selectively receiveinput light from only the portion of the environment illuminated by theilluminator, while receiving input with substantially the entire activearea of the photoreceptor array 132.

FIG. 5-1 and FIG. 5-2 schematically illustrate an embodiment of theadjustable optics of a 3D imaging system. FIG. 5-1 illustrates theadjustable optics of an illuminator 204. The illuminator 204 includes alight source 242 that produces an emitted light 244. The emitted light244 is collimated by a collimator 246 into a collimated light 248,which, in turn, passes to a beam broadener 250, such as a diffuser. Thediffused light 252 may then be directed by a movable illuminator lens254. The movable illuminator lens 254 may be moved axially (i.e.,relative to the light source 242) to change the angle of the FOI of anoutput light from the short throw FOI 208 to the long throw FOI 212, orany FOI therebetween.

In other embodiments, the illuminator 204 includes a plurality ofmovable illuminator lenses to alter the FOI of the illuminator 204. Forexample, the illuminator 204 may include a lens stack including aplurality of lenses where the lens stack is movable as set. In otherexamples, the illuminator 204 may include a plurality of movableilluminator lenses 254 that are independently moveable relative to thelight source 242.

In some embodiments, the movable illuminator lens 254 includes or ismade of glass. A glass lens may experience less change in optics due tothermal effects during use than a polymer lens or other material. Inother embodiments, at least one of the collimator, diffuser, andilluminator lens 254 includes or is made of a poly acrylic,polycarbonate, or other material.

FIG. 5-2 is a schematic representation of adjustable optics of animaging sensor 206, according to the present disclosure. In someembodiments, the imaging sensor 206 includes at least a photoreceptor256 and one or more movable imaging lenses 258. In other embodiments,the imaging sensor 206 may include additional lenses positioned betweenthe one or more movable imaging lenses 258.

In some embodiments, the imaging sensor 206 includes bandpass filter 252configured to attenuate light outside of the first wavelength range,described in relation to FIG. 1. For example, light may be received bythe one or more movable imaging lenses 258, and the focused light 260may be directed toward the bandpass filter 252 positioned proximate thephotoreceptor 256. The bandpass filter 252 may transmit more light inthe first wavelength range than light outside the first wavelengthrange. For example, the focused light 260 approaching the bandpassfilter 252 may include reflected light from the illuminator in the firstwavelength range, as well as ambient light. The bandpass filter 252 mayattenuate at least part of the ambient light portion to increase therelative proportion of reflected light from the illuminator in theincoming light.

The movable imaging lens 258 may be moved axially (i.e., relative to thephotoreceptor 256) to change the angle of the FOV of an input light fromthe short throw FOV 210 to the long throw FOV 214, or any FOVtherebetween.

In other embodiments, the imaging sensor 206 includes a plurality ofmovable imaging lenses 258 to alter the FOV of the imaging sensor 206.For example, the imaging sensor 206 may include a lens stack including aplurality of lenses where the lens stack is movable as set. In otherexamples, the imaging sensor 206 may include a plurality of movableimaging lenses 258 that are independently moveable relative to thephotoreceptor 256.

In some embodiments, the movable imaging lens 258 includes or is made ofglass. A glass lens may experience less change in optics due to thermaleffects during use than a polymer lens or other material. In otherembodiments, the imaging lens 258 includes or is made of a poly acrylic,polycarbonate, or other material.

FIG. 6 illustrates another embodiment of a 3D imaging system 300according to the present disclosure. In some embodiments, the 3D imagingsystem 300 includes a structured light illuminator 304 to provide aknown pattern of illumination to a target or object 322 in theenvironment. The 3D imaging system 300 may include a housing 302 thatincludes a processor 301 in data communication with the structured lightilluminator 304 and an imaging sensor 306. The processor 301 may receiveimage information from the imaging sensor 306 to calculate depth of theimage information.

FIG. 6 illustrates the 3D imaging system 300 in a short range operation.The structured light illuminator 304 is operating with a short throw FOI308 to project a pattern of structured light onto the object 322. In theillustrated example, the object is a user's hand for gesture tracking.The imaging sensor 306 may receive light from at least part of thepattern of structured light within the short throw FOV 310. The receivedlight from the pattern of structured light may be used by the processor306 to determine any shift or displacement in the pattern. The shift ordisplacement may be used to calculate the depth of the object 322imaged.

The measured shift or displacement of the projected pattern may be atleast partially dependent upon the displacement 362 of the structuredlight illuminator 304 and the imaging sensor 306. In some embodiments,the displacement 362 is in a range having an upper value, a lower value,or upper and lower values including any of 0.5 cm, 1.0 cm, 2.0 cm, 3.0cm, 4.0 cm, 5.0 cm, 6.0 cm, 7.0 cm, 8.0 cm, 9.0 cm, 10 cm, 15 cm, 20 cm,30 cm, 40 cm, 50 cm, 1.0 m, or any values therebetween. For example, thedisplacement 362 may be greater than 0.5 cm. In other examples, thedisplacement 362 may be less than 1.0 m. In yet other examples, thedisplacement 362 may be between 0.5 cm and 1.0 m. In further examples,the displacement 362 may be between 1.0 cm and 10 cm.

The 3D imaging system 300 of FIG. 6 may have a short throw FOI 308 andshort throw FOV 310 with dimensions such as those described in relationto the short throw FOI 108 and short throw FOV 110 described in relationto FIG. 1 through FIG. 2. Additionally, the 3D imaging system 300 ofFIG. 6 is illustrated in a long throw operational mode in FIG. 7, andthe long throw FOI 312 and long throw FOV 314 of FIG. 7 may havedimensions similar to the long throw FOI 112 and long throw FOV 114described in relation to FIG. 1 and FIG. 3.

The 3D imaging of a long range object 324 with a structured lightilluminator 304 may be at least partially dependent on the density ofthe structured light pattern projected on the object 324 and the FOVand/or resolution of the sensor 306. In a conventional system, thepattern diverges and the spatial resolution of the structured lightpattern degrades. By narrowing the FOI from the short throw FOI 308 inFIG. 6 to the long throw FOI 312 shown in FIG. 7, the density of thestructured light pattern is maintained over a longer distance.

To precisely measure the location and any shift and/or displacement ofthe structured light pattern, the imaging sensor 306 may be adjusted tonarrow the FOV to the long throw FOV 314 shown in FIG. 7. The long throwFOV 314 may allow for a higher angular resolution of the imaging sensor306 to more precisely measure changes in the structured light pattern,improving depth calculations.

FIG. 8 illustrates a schematic representation of an embodiment ofadjustable optics in a structured light illuminator 304 according to thepresent disclosure. The structured light illuminator 304 includes alight source 342 that produces an emitted light 344. The emitted light344 is collimated by a collimator 346 into a collimated light 348,which, in turn, passes to a structured light optical element 364, suchas a diffraction grating, to produce the structured light 365. Thestructured light 365 may then be directed by a movable illuminator lens354. The movable illuminator lens 354 may be moved axially (i.e.,relative to the light source 342) to change the angle of the FOI of anoutput light from the short throw FOI 308 to the long throw FOI 312, orany FOI therebetween.

FIG. 9 through FIG. 12 illustrate 3D imaging systems 400, 500 thatinclude a plurality of imaging sensors configured to measure disparityof an object within the FOV of the first imaging sensor and the FOV ofthe second imaging sensor. The stereoscopic vision of the plurality ofimaging sensors uses triangulation to determine depth values. Astereoscopic 3D imaging system may utilize active illumination from anilluminator in the 3D imaging system and/or use passive illuminationfrom ambient light. Stereoscopic vision, therefore, may be used inoutdoor applications with less concern for interference or noiseintroduced by ambient light, such as sunlight.

Optionally, an active illuminator 404 may be used to provide additional“texture” to the environment to assist in stereoscopic depthmeasurements. For example, some environments or object may have littleto no texture on a surface. Detecting and measuring any disparity inbetween the two or more imaging sensors of the 3D imaging system may bedifficult in such environments. An active illuminator may provide somevariation across the surface to enhance contrast.

In a stereoscopic 3D imaging system, such as that shown in FIG. 9, adisplacement 462 of the illuminator 404 and the imaging sensor 406-1,406-2 may allow for improved detecting of low contrast surfaces. Inother applications, a high contrast object 422, such as the hand shownin FIG. 9, may be detected more precisely in environments with lowamounts of ambient illumination. A 3D imaging system 400 with aplurality of imaging sensors 406-1, 406-2 and an active illuminator 404may selectively run the illuminator 404 when beneficial, while savingthe power when in an environment with sufficient ambient lighting.

Similarly to the active illuminators described herein, the illuminator404 have a variable focal length to adapt the FOI between the shortthrow FOI 408 illustrated in FIG. 9 and the long throw FOI 412illustrated in FIG. 10 to provide tailored illumination in aiding thestereoscopic depth measurements.

The housing 402 of the 3D imaging system 400 may be substantially rigidhousing or otherwise restrict the movement of the first imaging sensor406-1 and second imaging sensor 406-2 relative to one another. Thedistance between the first imaging sensor 406-1 and second imagingsensor 406-2 may, therefore, be a fixed baseline 466. The precision ofthe depth measurements of the stereoscopic 3D imaging system 400 isrelated to the baseline 466 by:

${{Average}\mspace{14mu} {Bias}\mspace{14mu} {Error}} = {{{mean}\left( {{Lens}\mspace{14mu} {EFL}*\frac{Baseline}{{Estimated}\mspace{14mu} {disparity}}} \right)} - {{radial}\mspace{14mu} {depth}}}$

where the lens EFL is the effective focal length. The precision of thesystem therefore, can be improved by tailoring the focal length (andhence the FOV) of the imaging sensors 406-1, 406-2, to the depth of theobject 422.

The focal length of the imaging sensors 406-1, 406-2 may be changed asdescribed in relation to FIG. 5-2 between the short throw FOV 410-1,410-2 and the long throw FOV 414-1, 414-2 illustrated in FIG. 9 and FIG.10. The FOV of the first imaging sensor 406-1 and the second imagingsensor 406-2 may be fixed relative to one another. For example, thefirst imaging sensor 406-1 and the second imaging sensor 406-2 may bothhave a short throw FOV 410-1, 410-2 at the same time and may changefocal length together as the first imaging sensor 406-1 and the secondimaging sensor 406-2 change toward a long throw FOV 414-1, 414-2 toimage the distance object 424 illustrated in FIG. 10. Having the focallength of the first imaging sensor 406-1 and the second imaging sensor406-2 tied to one another may ensure that any image comparison performedby a processor 401 may be performed with images of the same FOV.

In other embodiments, the 3D imaging system is a fully passivelyilluminated system, such as the 3D imaging system 500 illustrated inFIG. 11 and FIG. 12. The first imaging sensor 506-1 is continuouslyadjustable from a short throw FOV 510-1 for close depth measurements andtracking of an object 522 shown in FIG. 11 to a long throw FOV 514-1shown in FIG. 12 for ranged depth measurements and tracking of an object524. The second imaging sensor 506-2 is continuously adjustable from ashort throw FOV 510-2 shown in FIG. 11 to a long throw FOV 514-2 shownin FIG. 12.

Because the housing 502 is a fixed housing, the baseline 566 remainsconstant between operating distances. As described in relation to FIG. 9and FIG. 10, the focal length of the first imaging sensor 506-1 and thefocal length of the second imaging sensor 506-2 may be fixed relative toone another, such that any images communicated to the processor 501 areof the same FOV, irrespective of the focal length.

Adjusting the FOI and/or FOV of a 3D imaging system may have furtherbenefits, as well. For example, conventional 3D imaging systems withactive illumination encounter uncertainty in depth calculations nearsidewalls of a room or object because active illumination can followmultiple paths to or from an imaged point.

FIG. 13 illustrates such a “multipath” situation, wherein a 3D imagingsystem 600 with an illuminator 604 and an imaging sensor 606 mayexperience uncertainty. The 3D imaging system 600 is attempting to imagean endwall 668 of a room near a sidewall 670. The wide-angle short throwFOI 608 has diverging light 672 centered about a center axis 674. In theillustrated example, the diverging light 672 may reflect from thesidewall 670 and converge at a common point 676 with the center axis674. In a 3D imaging system 600 with active illumination (either atime-of-flight 3D imaging system or a structured light 3D imagingsystem), having multiple paths of different lengths converging at acommon point 676 will introduce error. A 3D imaging system withadjustable FOI and/or FOV, however, may alter the first angular width678 relative to the center axis 676 of the FOI and/or FOV to avoidilluminating the sidewall 670.

FIG. 14 illustrates the 3D imaging system 600 of FIG. 13 with a narrowersecond angular width 680 relative to the center axis 676 in the longthrow FOI 612. The focal length of the illuminator 604 may be altered toreduce the lateral dimension of the FOI and prevent illumination of thesidewall, such that all output light from the illuminator 604 contactsthe endwall 668 first. By aligning the FOI and the FOV, as describedabove, the FOV may further avoid capturing light reflected from thesidewall after encountering the endwall (e.g., the multipath of FIG. 13in reverse). FIG. 14 illustrates a long throw FOI 612 that is narrowerthan the short throw FOI 608 of FIG. 13. Both the long throw FOI 612 andthe short throw FOI 608 are centered about the center axis 674.

FIG. 15 illustrates another example of avoiding a multipath situationwith a 3D imaging system 600 with adjustable optics. The illuminator 604may have an aperture thereon that is movable laterally to bias the FOIin a lateral direction. While the center axis 676 may remainsubstantially normal to the endwall 668, the portion of the FOIproximate the sidewall 670 may be partially eclipsed such that theportion of the FOI proximate the sidewall 670 effectively has thenarrower second angular width 680 relative to the center axis 676. Theportion of the FOI farther from the sidewall 670 may be unaltered, andthe portion of the FOI farther the sidewall 670 may have the wider firstangular width 678.

Similarly, conventional 3D imaging systems experience uncertainty atincreasing distances relative to the angular FOV. The standard deviationin such uncertainty is commonly referred to as “jitter” because theuncertainty can result in depth calculations that vary along a knownflat surface. Jitter is primarily caused by the worsening angularresolution of a 3D imaging system as the depth of field increases. Theeffective area that is represented by each pixel becomes larger and thedepth calculations for that particular area can become uncertain. A 3Dimaging system with adjustable optics, according to the presentdisclosure, may lessen jitter uncertainty. For example, in simulationsconducted for a passive stereoscopic 3D imaging system with a baselineof 40 mm and an imaging sensor resolution of 1024 by 1024 pixels, a 65°FOV yielded reasonable jitter and reliable depth calculations up to 1.0meter of depth (i.e., less than 15 mm of jitter). However, farther than1 meter, the jitter renders the system unreliable. Reducing the FOV toabout 20° while keeping the baseline constant allows the system toreliable calculate depth measurements up to 2.0 meter of depth beforeexperiencing an equivalent jitter of 15 mm.

In any of the embodiments of a 3D imaging system with adjustable optics,the system will be calibrated at a plurality of distances to accuratelymeasure depth of the image while factoring for intrinsic parameters andgeometric distortion. In some embodiments, the 3D imaging system iscalibrated by measuring the geometric distortion at different effectivefocal lengths to allow the system to compensate for the changes inoptical behavior with changes to the optics. In other embodiments, the3D imaging system is calibrated by machine learning. A known object ortarget may be positioned at a known relationship to the 3D imagingsystem and the dimensions and/or position of the object may be providedto the 3D imaging system. The process is repeated at different positionsrelative to the 3D imaging system and the 3D imaging system (e.g., theprocessor) may infer the appropriate corrections to correlate theprovided known values as the object is moved.

The adjustments to the optics of a 3D imaging system (e.g., changingFOI, changing FOV, or both) may be performed manually by a user or madeautomatically in response to one or more triggers. For example, FIG. 16illustrates a flowchart 1600 depicting a method of 3D imaging usingadjustable optics.

The method may include emitting an output light from an illuminator at1602 to illuminate a target or an environment. Upon receiving a triggerat 1604, the system may change the field of illumination of anilluminator at 1606 and/or the field of view of an imaging sensor at1608.

In some embodiments, the trigger is provided by the 3D imaging system,itself. For example, the trigger may be the calculation of a jittervalue above a predetermined threshold (e.g., 30 mm of jitter). Inanother example, the trigger may be detection uncertainty that may bedue to a multipath error. In yet another example, the trigger may be thedetection of a close-range object moving through the FOV rapidly (e.g.,a hand gesture that a narrow FOV only partially captures).

In other embodiments, the trigger is provided by a software applicationin communication with the 3D imaging system. For example, when the 3Dimaging system is used in a head mounted device, a software applicationfor displaying interactive models to a user may instruct the 3D imagingsystem to decrease the effective focal length of the imaging sensor(s)to increase hand tracking for interacting with the models. In anotherexample, with the 3D imaging system is used in video conferencingsystem, a software application may be set to a “room” mode to instructthe 3D imaging system to increase the focal length to image objects allthe way at an opposite wall of the room.

In yet other embodiments, the trigger is received from one or moresensors in data communication with the 3D imaging system. For example,the trigger may be received from an ambient light sensor, instructingthe 3D imaging system to narrow the FOI and/or FOV to increaseillumination concentration and angular resolution in an effort tocompensate for high amounts of ambient light. In other examples, such aswhen the 3D imaging system used in or on a vehicle, an accelerometer,GPS sensor, speedometer, or other movement tracking device may instructthe 3D imaging system to either narrow or broaden the FOI and/or FOVdepending at least partially upon velocity and/or acceleration of the 3Dimaging system.

Upon receiving changing the field of illumination and/or changing thefield of view, the system may detect reflected light at 1610 includingat least part of the output light of the illuminator and measure one ormore a depth values of the FOV at 1612 based upon the time-of-flight,the distortion and/or shift of the structured light, or the disparity inimages (when the 3D imaging system has a plurality of imaging sensors).

FIG. 17 is a flowchart 1700 illustrating an embodiment of a method of 3Dimaging using a passive stereoscopic system. The method includesreceiving a trigger at 1702, such as any of the triggers describedabove, and changing the field of view of a first imaging sensor and asecond imaging sensor at 1704. After changing the field of view, themethod includes detecting reflected light at 1706 with a first imagingsensor and a second imaging sensor and measuring at least one depthvalue of the images collected at 1708 by comparing the signal from thefirst imaging sensor and the signal from the second imaging sensor.

Embodiments of the present invention may comprise or utilize a specialpurpose or general-purpose computer including computer hardware, asdiscussed in greater detail below. Embodiments within the scope of thepresent invention also include physical and other computer-readablemedia for carrying or storing computer-executable instructions and/ordata structures. Such computer-readable media can be any available mediathat can be accessed by a general purpose or special purpose computersystem. Computer-readable media that store computer-executableinstructions are physical storage media. Computer-readable media thatcarry computer-executable instructions are transmission media. Thus, byway of example, and not limitation, embodiments of the invention cancomprise at least two distinctly different kinds of computer-readablemedia: physical computer-readable storage media and transmissioncomputer-readable media.

Physical computer-readable storage media includes RAM, ROM, EEPROM,CD-ROM or other optical disk storage (such as CDs, DVDs, etc.), magneticdisk storage or other magnetic storage devices, or any other mediumwhich can be used to store desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer.

A “network” is defined as one or more data links that enable thetransport of electronic data between computer systems and/or modulesand/or other electronic devices. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to acomputer, the computer properly views the connection as a transmissionmedium. Transmissions media can include a network and/or data linkswhich can be used to carry or desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer. Combinationsof the above are also included within the scope of computer-readablemedia.

Further, upon reaching various computer system components, program codemeans in the form of computer-executable instructions or data structurescan be transferred automatically from transmission computer-readablemedia to physical computer-readable storage media (or vice versa). Forexample, computer-executable instructions or data structures receivedover a network or data link can be buffered in RAM within a networkinterface module (e.g., a “NIC”), and then eventually transferred tocomputer system RAM and/or to less volatile computer-readable physicalstorage media at a computer system. Thus, computer-readable physicalstorage media can be included in computer system components that also(or even primarily) utilize transmission media.

Computer-executable instructions comprise, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing device to perform a certain function orgroup of functions. The computer-executable instructions may be, forexample, binaries, intermediate format instructions such as assemblylanguage, or even source code. Although the subject matter has beendescribed in language specific to structural features and/ormethodological acts, it is to be understood that the subject matterdefined in the appended claims is not necessarily limited to thedescribed features or acts described above. Rather, the describedfeatures and acts are disclosed as example forms of implementing theclaims.

Those skilled in the art will appreciate that the invention may bepracticed in network computing environments with many types of computersystem configurations, including, personal computers, desktop computers,laptop computers, message processors, hand-held devices, multi-processorsystems, microprocessor-based or programmable consumer electronics,network PCs, minicomputers, mainframe computers, mobile telephones,PDAs, pagers, routers, switches, and the like. The invention may also bepracticed in distributed system environments where local and remotecomputer systems, which are linked (either by hardwired data links,wireless data links, or by a combination of hardwired and wireless datalinks) through a network, both perform tasks. In a distributed systemenvironment, program modules may be located in both local and remotememory storage devices.

Alternatively, or in addition, the functionality described herein can beperformed, at least in part, by one or more hardware logic components.For example, and without limitation, illustrative types of hardwarelogic components that can be used include Field-programmable Gate Arrays(FPGAs), Program-specific Integrated Circuits (ASICs), Program-specificStandard Products (ASSPs), System-on-a-chip systems (SOCs), ComplexProgrammable Logic Devices (CPLDs), etc.

The articles “a,” “an,” and “the” are intended to mean that there areone or more of the elements in the preceding descriptions. The terms“comprising,” “including,” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Numbers,percentages, ratios, or other values stated herein are intended toinclude that value, and also other values that are “about” or“approximately” the stated value, as would be appreciated by one ofordinary skill in the art encompassed by embodiments of the presentdisclosure. A stated value should therefore be interpreted broadlyenough to encompass values that are at least close enough to the statedvalue to perform a desired function or achieve a desired result. Thestated values include at least the variation to be expected in asuitable manufacturing or production process, and may include valuesthat are within 5%, within 1%, within 0.1%, or within 0.01% of a statedvalue.

A person having ordinary skill in the art should realize in view of thepresent disclosure that equivalent constructions do not depart from thespirit and scope of the present disclosure, and that various changes,substitutions, and alterations may be made to embodiments disclosedherein without departing from the spirit and scope of the presentdisclosure. Equivalent constructions, including functional“means-plus-function” clauses are intended to cover the structuresdescribed herein as performing the recited function, including bothstructural equivalents that operate in the same manner, and equivalentstructures that provide the same function. It is the express intentionof the applicant not to invoke means-plus-function or other functionalclaiming for any claim except for those in which the words ‘means for’appear together with an associated function. Each addition, deletion,and modification to the embodiments that falls within the meaning andscope of the claims is to be embraced by the claims.

The terms “approximately,” “about,” and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately,” “about,” and “substantially” may refer to an amountthat is within less than 5% of, within less than 1% of, within less than0.1% of, and within less than 0.01% of a stated amount. Further, itshould be understood that any directions or reference frames in thepreceding description are merely relative directions or movements. Forexample, any references to “up” and “down” or “above” or “below” aremerely descriptive of the relative position or movement of the relatedelements.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or characteristics. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive. The scope of the invention is, therefore, indicated by theappended claims rather than by the foregoing description. All changeswhich come within the meaning and range of equivalency of the claims areto be embraced within their scope.

What is claimed is:
 1. A method of three-dimensional imaging, the methodincluding: emitting an output light with a structured light illuminatorin a structured light pattern; receiving a trigger command; changing afield of illumination of the illuminator; changing a field of view of animaging sensor, wherein the field of view and the field of illuminationare linked, such that the field of view of the imaging sensor is thesame as the field of illumination of the illuminator at a short throwfield of view and a long throw field of view; detecting a reflectedlight with the imaging sensor; and measuring a depth value bycalculating a distortion of the structured light pattern.
 2. The methodof claim 1, wherein the trigger command is received from a softwareapplication.
 3. The method of claim 1, wherein the trigger command isreceived from the imaging sensor detecting an optical multipath.
 4. Themethod of claim 3, wherein changing the field of illumination and thefield of view includes changing a first angular width relative to acenter axis of the field of illumination and field of view.
 5. Themethod of claim 1, wherein the trigger command is received from one ormore sensors in data communication with the 3D imaging system.
 6. Themethod of claim 1, wherein changing the field of illumination includeschanging the field of illumination from a first field of illumination toa second field of illumination, and changing the field of view includeschanging the field of view from a first field of view to a second fieldof view, the second field of illumination and the second field of viewbeing approximately equivalent.
 7. The method of claim 6, wherein thefield of view and field of illumination remain approximately equivalentwhile changing the field of view and field of illumination.
 8. Themethod of claim 1, wherein the trigger command is at least partiallybased on environmental information.
 9. The method of claim 1, whereinchanging the field of illumination includes changing an illuminationpower of the illuminator.
 10. The method of claim 1, wherein thestructured light illuminator emits light in an infrared wavelengthrange.
 11. A method of three-dimensional imaging, the method including:emitting an output light with a structured light illuminator in astructured light pattern; receiving a trigger command from one or moresensors in data communication with the 3D imaging system; changing afield of illumination of the illuminator from a long throw field ofillumination to a short throw field of illumination; changing a field ofview of an imaging sensor from a long throw field of view to a shortthrow field of view, wherein the field of view and the field ofillumination are linked, such that the short throw field of illuminationand short throw field of view are approximately the same and the longthrow field of illumination and short throw field of view areapproximately the same; detecting a reflected light of the structuredlight pattern with the imaging sensor; and measuring a depth value bycalculating a distortion of the structured light pattern.
 12. The methodof claim 11, further comprising detecting an optical multipath with theone or more sensors, wherein the trigger command includes detection ofthe optical multipath.
 13. The method of claim 11, wherein theilluminator has a field of illumination range between a 10° range and a120° range.
 14. The method of claim 11, wherein the imaging sensor has afield of view range between a 10° range and a 120° range.
 15. The methodof claim 11, wherein the output light is in a first wavelength range.16. The method of claim 15, further comprising attenuating a portion ofthe reflected light outside the first wavelength range with a bandpassfilter.
 17. The method of claim 15, wherein the output light is in aninfrared wavelength range.
 18. The method of claim 11, wherein changingthe field of illumination includes changing a geometry of the structuredlight pattern emitted by the illuminator.
 19. A method ofthree-dimensional imaging, the method including: emitting an outputlight with a structured light illuminator positioned in a head-mounteddisplay, wherein the output light is emitted in a structured lightpattern; receiving a trigger command from one or more sensors in datacommunication with the head-mounted display; changing a field ofillumination of the illuminator; changing a field of view of an imagingsensor positioned in the head-mounted display, wherein the field of viewand the field of illumination are linked, such that the field of view ofthe imaging sensor is the same as the field of illumination of theilluminator at a short throw field of view and a long throw field ofview; detecting a reflected light with the imaging sensor; and measuringa depth value by calculating a distortion of the structured lightpattern.
 20. The method of claim 19, wherein a portion of the reflectedlight is reflected from a user's hand, and further comprising tracking agesture input of the user's hand.